Reheat combustion equipment



Nov. 14, 1967 N. E. PAYNE REHEAT COMBUSTION EQUIPMENT Filed June 21, 1965 lnvenlor Attorneys United States Patent 3,352,113 REHEAT COMBUSTION EQUIPMENT Nigel Edward Payne, Repton, England, assignor to Rolls- Royce Limited, Derby, England, a British company Filed June 21, 1965, Ser. No. 465,513 Claims priority, application Great Britain, Aug. 19, 1964, 33,983/ 64 1 Claim. (Cl. 60-261) ABSTRACT OF THE DISCLOSURE An arrangement in the exhaust duct of a gas turbine engine for providing reheat combustion comprising a main reheat combustion equipment including means for introducing fuel into the exhaust gases, a gutter arrangement to provide a sheltered zone for combustion downstream of the means for introducing fuel, and a device upstream of the main reheatcombustion equipment in a region of relatively higher exhaust temperature, the device initiating combustion in the downstream main reheat equipment. The device includes means to introduce additional fuel into the exhaust gases, a gutter downstream therefrom for providing a sheltered zone in the region of higher temperatured exhaust gases, and a catalytic igniter for promotion of ignition of the fuel at the gutter in the region of higher temperatured exhaust gases.

This invention concerns a reheat combustion equipment assembly for a gas turbine engine.

According to the present invention there is provided a reheat combustion equipment assembly for a gas turbine engine comprising means for introducing fuel into the exhaust gases of the engine, a gutter arrangement for providing a sheltered zone in which combustion of said fuel may occur and a device disposed upstream of said means and gutter arrangement for initiating combustion in said equipment, said device comprising further means for introducing additional fuel into said exhaust gases, an igniter of catalytic material for promoting ignition of said additional fuel and a further gutter arrangement for providing a further sheltered zone in which combustion of said additional fuel may occur, the hot combustion gases from said device initiating combustion in said combustion equipment.

Preferably the igniter of catalytic material is of the form shown in any of our British Patent Nos. 934,499, 944,202 or 948,578.

The assembly may be disposed within an exhaust duct of a gas turbine engine said further gutter being linear (i.e. of rectangular cross section as opposed to annular or circular cross sections) and extending radially within the exhaust duct.

The further means for introducing additional fuel into the exhaust gases may comprise an apertured hollow probe extending into said exhaust duct and being radially disposed therein, the probe being disposed upstream of and being aligned with said further gutter.

Preferably the said igniter and further gutter are aligned radially, said hollow probe extending over the combined radial extent of said igniter and further gutter and being apertured over said radial extent whereby fuel may be introduced into the gases flowing to said igniter and said further gutter. In one embodiment the igniter and further gutter may be mounted on the exhaust cone of said engine, said probe being mounted :on the surrounding engine casing. Thus the casing may constitute the inner wall of a by-pass duct of said engine, the by-pass duct communicating with said exhaust duct between said means and gutter arrangement and said device.

The invention also includes a gas turbine engine pro- 3,3511 13 Patented Nov. 14, 1967 vided with a reheat combustion equipment assembly as set forth above.

The invention is illustrated merely by way of example in the accompanying drawings, in which:

FIGURE 1 is a cut-away view of a gas turbine engine provided with a reheat combustion equipment assembly according to the present invention, and

FIGURE 2 is a general view of part of the engine of FIGURE 1 in more detail.

Referring to the drawings there is shown a gas turbine jet propulsion by-pass engine 10 comprising a compressor 11, combustion equipment 12, turbine 13 and an exhaust pipe 14 all mounted in axial flow series. A by-pass duct 15 extends from the compressor 11 to the jet pipe 14 bypassing the combustion equipment 12 and the turbine 13.

Mounted within the jet pipe 14 is a reheat combustion equipment assembly for boosting the thrust of the engine, the assembly comprising radially disposed probes 16, 17 for introducing fuel into the gases flowing through the jet pipe 14 and a plurality of annular gutters 18 providing sheltered zones within which combustion of the fuel/ air mixture may occur.

Ignition of the exhaust gases and fuel adjacent the gutters 18 is initiated by a device 20 mounted upstream of the probes 16, 17 and gutters 18 and shown in more detail in FIGURE 2.

The device 20 comprises a cylindrical catalytic igniter 21 of the type described and claimed, for example, in any of our British Patent Nos. 934,499, 944,202 or 948,578. The igniter 21 is mounted in a cylindrical housing 22 having a flared downstream end 23 and this in turn is mounted within a housing 24 supported from a exhaust cone 25 of the engine by a yoke 26.

Radially aligned with and fixed to the cylindrical housing 22 containing igniter 21 is a linear gutter 27 in the form of a rectangular box having an open downstream end. The gutter 27 extends radially within the exhaust pipe of the engine.

Mounted directly upstream and aligned with the combined gutter 27 and housing 22 with igniter 21 is -a probe 30 which is both hollow and apertured and extends from an engine casing 31 radially inwardly over the radial extent of the combined gutter 27 and cylindrical housing 22. Apertures in the probe 30 extend over the radial extent covered by the gutter 27 and cylindrical housing 22 and fuel introduced into the probe 30 through fuel line 32 mixes with the gases flowing through the exhaust duct 14 from the turbine 13, and a fuel/air mixture passes to the gutter 27 and to the igniter 21.

The igniter 21 promotes ignition of the fuel/air mixture flowing therethrough and the ignited mixture promotes combustion of the fuel/ air mixture within the sheltered zone formed by gutter 27. The hot combustion gases from the device 20 flow downstream and initiate combustion of the fuel/ air mixture within the sheltered zones downstream of gutters 18.

It will be appreciated that the radial extent of the device 20 dictates the size of the streak of hot gases which are used to initiate combustion of the fuel/air mixture adjacent gutters 18. The wider the radial extend of the hot gases the better is the light up of the reheat combustion equipment.

It will be appreciated that the igniter 21 and gutter 27 and the probe 30 may be inverted in position i.e. the igniter 21 and gutter 27 may be supported from the casing 31 and the probe 30 may project from the bullet 25. The igniter 21 need not be catalytic but could be the normal electrical igniter employed in conventional reheat systems.

The reheat device described above is not restricted to use in gas turbine by-pass engines, but may be used on any gas turbine engine employing reheat.

I claim:

In a gas turbine engine exhaust duct including an exhaust core and a surrounding casing, a reheat combustion equipment assembly comprising means for introducing fuel into the exhaust gases of the engine, a gutter arrangement for providing a sheltered zone in which combustion of said fuel may occur and a device disposed upstream of said means and gutter arrangement for initiating combustion in said equipment, said device comprising an apertured hollow probe extending into said exhaust duct and being radially disposed therein, for introducing additional fuel into said exhaust gases, an igniter for promoting ignition of said additional fuel and a further gutter arrangement comprising a single linear gutter disposed downstream of and aligned with said probe and providing a further sheltered zone in which combustion of said additional fuel may occur, the hot combustion gases from said device initiating combustion in said combustion equipment, said igniter and further gutter being aligned radially and mounted on said exhaust cone and said hollow probe being mounted on said casing and extending over the combined radial extent of said igniter and further gutter and being apertured over said radial extent whereby fuel may be introduced into the gases flowing to said igniter and said further gutter.

References Cited UNITED STATES PATENTS 2,679,137 5/1954 Probert 60-39.72 2,804,241 8/1957 McDoWall 60-261 2,963,857 12/1960 Egbert 60-26l 3,118,276 l/ 1964 Keenan 60-261 3,150,484 9/1964 Oldfield 60261 3,156,094 11/1964 Nash 60-3982 FOREIGN PATENTS 66,338 4/ 1956 France.

MARK M. NEWMAN, Primary Examiner.

CARLTON R. CROYLE, Examiner.

D. HART, Assistant Examiner. 

